The trend in the automobile industry is towards increased use of plastic body panels in automobile construction. Use of such panels makes it possible to reduce the weight of the automobiles and also to reduce tooling costs arising from body styling changes, while providing increased styling freedom in car design. Other advantages arising from this type of construction include reduced facility costs and factory floor space requirements, and process cycle times allowing the just-in-time, low inventory manufacturing of parts at or near the automobile assembly plant. See C. Kirkland and P. Dickard, Dateline: Detroit. SAE Show News Bulletins, Plastic Technology, page 103 (April 1986).
A significant problem with plastic automobile body parts is that many of the most desirable molding polymers for such parts are not weatherable. Moreover, many such polymers do not provide a good bonding surface for paints. Even where paint bonding problems are overcome, conventional spray-painting techniques pose a significant pollution problem arising from the evaporation of noxious paint solvents, and, further, are very expensive if a high quality, multiple coat paint finish is to be obtained. Because the overall finished appearance of an automobile is among its most important selling features, these problems are serious, and a great deal of effort and expense is being devoted to their solution. See, for example, Automotive Coatings: Helping Detroit Woo Consumers, Chemical Week, page 30, (Jul. 4, 1984). One approach to this problem is to provide a film surface for the plastic part.
Various molded polymer automobile parts with film surfaces have been made in the past. For example, clear, unpigmented, nonweatherable, cast PVC films have been used to surface interior automobile parts. Another example, U.S. Pat. No. 3,679,510 to Conley and Ellison, discloses a reverse-printed, oriented, polyvinyl fluoride film (a "TEDLAR" film) bonded to a molded polymer substrate. Such weatherable, oriented films are excellent for use in making side rails and other automobile trim parts. These films are, however, difficult to uniformly internally pigment, and are generally not suitable for use in a deep draw molding procedure. In order to be useful as a surfacing film on exterior automobile parts, the film must duplicate the surface appearance of a quality automobile paint finish. The finish must have high gloss, high distinctness of image (DOI), excellent weatherability and durability under exposure to sunlight and temperature extremes, and the film must match the solid and metallic colors used in automobile paint finishes.
Accordingly, an object of the present invention is to provide a molded polymer article which has a weatherable surface.
A further object of the invention is to provide an article as described above which has a high grade decorative finish suitable for use as an automobile body part.
An additional object of the invention is to provide an article of the type described which can be deep draw molded into various three-dimensional shapes used in automobile body parts.